How to make a mod that's an addon of a different mod?

I want to make an addon for the Create mod, particularly one that adds structures to the worldgen that use the create blocks, but I cannot figure out how to make a mod in MCreator that uses the existing Create mod. I've tried for a while to find any resources on how to accomplish this, but to no avail. If someone could point me to a resource that explains how to hook up a mod like Create to my workspace or whatever else may be required to set up the dependency accurately and run the test client with Create added, that'd be great.

I assumed adding the Create mod to the workspace folder's run folder>mods would've done the trick, but when I do that the client never successfully launches.

I appreciate any direction you can provide. Thanks,
      -Kess